I created a new post but it doesn’t show up in the calendar. Why?

In the same way that you can schedule posts directly on the calendar, if you write a post and set a publication date on it, the post will automatically appear as scheduled on the calendar.

To schedule a post with a publication date, in the Status & Visibility box of the Document properties, click on immediately link next to Publish. There you can select the publication date and apply it.

Status & visibility of a post.
Status & visibility of a post.

Once you do that, you’ll see the post as scheduled in the editorial calendar of Nelio Content. Note that the calendar is completely synced with the WordPress post editor.